ASSESSMENT OF ENVIRONMENTAL POLLUTION OF WATER FROM IRRIGATION CANAL (ALEKSANDROVAČKI CANAL, SERBIA) USING PHYTO-INDICATORS
*Sonja Gvozdenac1, Dušanka Inđić1, Slavica Vuković1, Vojislava Bursić1 and Jelena Tričković2
1Faculty of Agriculture, University of Novi Sad, 21000 Novi Sad, Serbia
2Faculty of Science, University of Novi Sad, 21000 Novi Sad, Serbia
ASSESSMENT OF ENVIRONMENTAL POLLUTION OF WATER FROM IRRIGATION CANAL (ALEKSANDROVAČKI CANAL, SERBIA) USING PHYTO-INDICATORS
ABSTRACT
The aim of this study was to carry out comparative assessment of pollution level of water from Aleksandrovački canal, Serbia, using both chemical methods and phytoindicators, and to estimate its potential use for irrigation of four most commonly cultivated plant species in this area (maize, barley, cucumber and white mustard). The effect of water quality and/or pollution was assessed in bioassay, according to changes in physiological (seed germination energy, germination) and morphological parameters (root and shoot length -cm and fresh and dry weight of root and shoot-g) of tested species. The chemical analysis of water determined a high content of suspended substances, nutrients, ammonium ion, total nitrogen, organic matter with low degradability, total organic carbon, orthophosphates, total phosphorus, arsenic and chromium. The response of phyto-indicators to water quality and mixed pollution was species-dependant. Germination of maize, cucumber and white mustard was not under the influence of water quality, while barley seeds germinated in significantly lower percentage in water from the canal (95%) compared to the control (100%). Canals water inhibited root elongation of maize and barley and stimulated of white mustard (p<0.01) compared to the control. Shoot length of barley, cucumber and white mustard was not under the influence of water quality (p>0.05). Biomass was differently affected by water from the canal.
Key words: Canal water, pollution, irrigation, plants, bioindicators
INTRODUCTION
Inappropriate and frequent use of agrochemicals (pesticides and mineral fertilizers) and a discharge of untreated industrial effluents and sewage directly into the water reservoirs have led to contamination of water sources (Ashraf et al., 2008, Prica et al., 2010) including irrigation canals. This problem is more pronounced in industrial and agricultural regions, where water from canals is polluted with a variety of compounds, often has reduced level of dissolved oxygen and high nutrients content (Emmanuel et al., 2012), as well as pesticide residues originating from fields drainage (Schulz and Liess 1999). Generally the use of such water for irrigation, although benefits to farmers due to reduced costs, can be harmful for ecosystem (Ashraf et al. 2008), cause phyto-toxic effects and affect crop production (Schulz and Liess 1999). The occurrence of toxic affect on growth and development of cultivated crops after a long-term irrigation with water containing high levels of toxic substances was also reported by Liu et al. (2005). In terms of toxicity assessment, the use of water from irrigation canals presents a complex situation due to possible interactions between pollutants and plants. Therefore, to estimate the water quality and decide if it can be used for irrigation of certain crops it is necessary to perform a comparative study using both, chemical and biological methods for risk assessment. Biological tests that include agricultural plants as indicators of contamination have become a useful tool for the evaluation of quality of water that is used for irrigation in the last few years and for risk assessment of different organic and inorganic pollutants (Casa et al. (2003); Leitgib et al. (2007); D’Aquino (2009); Schultz et al. (2010); Gvozdenac et al. (2011)).
Aleksandrovački canal, Serbia, has been contaminated with a variety of compounds originating from industrial and domestic effluents and agricultural products from field drainage waters (pesticides and fertilizers run off). According to a long term monitoring it is considered extremely polluted, but it is still intensively used for irrigation of crops without thought of potential phytotoxic effects. Therefore, the aim of this study was to evaluate the quality and/or the level of pollution of water from this canal in comparative analysis using chemical and biological methods –plants as indicators, and to assess its suitability for irrigation of four most commonly cultivated plants (maize, barley, cucumber and white mustard) in this area.
MATERIALS AND METHODS
Water from Aleksandrovački canal was collected in 2011 at site N 45° 20.912' / E 20° 25.032'. Analyzed parameters of water quality and methods used for chemical analysis are presented in Table 1.
For bioassay, test species were chosen as the most commonly cultivated plants in this area– maize (Zea mays L.) variety NS 6030, barely (Hordeum vulgare L.) variety Novosadski 525, cucumber (Cucumis sativus L.) variety Tajfun and white mustard (Sinapis alba L.) variety Torpedo. The effect of water quality on plants was evaluated according to changes in physiological (seed germination energy, germination - %) and morphological parameters (root and shoot length -cm and fresh and dry weight of root and shoot -g).
Bioassay was carried out according to a standard filter paper method described by International Seed T Association: International Rules for Seed Testing- ISTA (2011). For germination assessment, 50 maize and 100 barely, cucumber and white mustard seeds were placed in plastic boxes on pleated filter paper, previously moistened with 25 mL of sampled water from the canal and distilled water for the control variant. Seeds were incubated in dark at 25±2 °C for three (white mustard) or four days (other species) after which 10 seedlings were taken from each replicate and placed on filter paper lane (14 x 60cm) previously moistened with 30ml of tested water sample, rolled up, packed in PVC bags and placed back in thermostat. Boxes with remained seeds were also returned in thermostat until the final germination assessment. After seven (maize, barley and white mustard) and eight (cucumber) days germination was recorded and length of seedlings roots and shoots and their fresh weight were measured. After the drying to the constant mass, the dry weight was also measured. Experiment was set in four replicates.
Data were analyzed using T test, for 95% confidence interval, in software SPSS version 17.0 (SPSS, Inc., Chicago IL).
Results and discussion
Chemical analysis
The chemical analysis of water from Aleksandrovački canal and classification according to Regulation on limit values for pollutants in surface and ground waters and sediments (Official gazette RS, 50/12) are presented in Table 1. Maximal allowable concentrations (MAC) used as limit values are for the III class of water according to the mentioned Regulation, because, respecting national directives only I, II and III class of water can be used for irrigation without prior treatment.
Chemical analysis detected high levels of: COD, BOD5, organic matter with low degradability (COD/BOD5 ratio 5.7) which results in almost total absence of oxygen, high conductivity, suspended substances, total nitrogen, ammonium ion, orthophosphates, total phosphorus, TOC, arsenic and chromium.
Table 1. General parameters and heavy metal content in water from Aleksandrovački canal
Surface waterParameter / Method / Values* / MAC for III class / Class based on detected values
COD / ISO 6060:1994 / 332 / 20 / V
BOD5 / H1.002 / 58 / 7 / V
Diluted oxygen / 0.8 / 5 / II
pH / 7.83 / 6.5 - 8.5 / II
conductivity / 3150 / 1500 / V
Suspended substances / APHA 2540D / 161 / 25
Dry residue / APHA 2540B / 1430 / -
Residue on ignition / APHA 2540E / 869 / -
Loss on ignition / calculate / 557 / -
Total nitrogen / calculate / 80.1 / 8 / V
Organic nitrogen / EPA 351.3 / 73,9 / -
Ammonium ion / APHA 4500-NH3 C:1989 / 5.99 / 0.6 / V
Nitrates / ISO 7890-3:1994 / 0.136 / 6 / I
Nitrites / ISO 6777:1997 / 0.099 / 0.12 / III
Orthophosphates / EPA 365.3 / 3.95 / 0.2 / V
Total phosphorus / EPA 365.3 / 6.98 / 0.4 / V
TOC / EPA 415.3 / 186 / 15 / V
Sulphates / 74.3 / 200 / II
Arsenic / EPA 7010 / 32.3 / 10 / IV
Cadmium / EPA 7010 / 0.15 / 1 / MAC-EQS
Chromium / EPA 7010 / 1330 / 100 / V
Copper / EPA 7010 / 50 / 500 / II
Lead / EPA 7010 / 5 / 5 / no MAC-EQS
Mercury / EPA 7010 / 0.17 / 0.1 / MAC-EQS
Nickel / EPA 7010 / 1.1 / 50 / no MAC-EQS
Zinc / EPA 7000b / 11 / 30 / I
Iron / EPA 7010 / 460 / 500 / II
Manganese / EPA 7010 / 79 / 100 / I
*all values are expressed in µg/L; MAC values are for the III class according to Regulation on limit values for pollutants in surface and ground waters and sediments (Official gazette RS, 50/12); Values in bold exceed maximal permissible limits
Bioassay
The results of bioassay, presented in Table 2, indicate that germination and seedlings early growth were differently affected by total chemistry of the water from Aleksandrovački canal and mixed pollution. This is in accordance with findings of Liu (2005) that tolerance levels of crops are species-dependant and vary under different stress intensities (concentrations and type of pollutants) and growth stages.
Germination of maize, cucumber and white mustard (F=0.70ns, 1.03ns, 1.77ns, P>0.05, respectively) was not under the influence of water quality. This is in accordance with previous reports of Gvozdenac et al. (2011, 2012) indicating that germination of maize and cucumber was not affected by the chemical composition of canal water containing elevated levels of organic nitrogen, ammonium ions, nitrates, nitrites, orthophosphate and total phosphorus as well as total organic carbon, cadmium, copper and nickel. On the other hand, germination of barley seeds was significantly inhibited in water from Aleksandrovački canal compared to the control (F=2.61*, P<0.05). This can be result of mixed pollution of water sample from the canal, or a specific component. According to some researchers high electrical conductivity, indicating at high salt content, increases osmotic pressure which causes germination retardation due to reduced available water content or toxicity of specific ions (Sheoron and Grag (1980); Ramana et al. (2002); Samuel and Muthukkaruppan (2012); Mehta and Bhardwaj (2012)). According to Pandey et al. (2007) this effect varies from crop to crop because each has its own tolerance to different salt concentrations. High COD and BOD5 can also cause inhibition of germination as reported by Samuel and Muthukkaruppan (2012) for rice and Mehta and Bhardwaj (2012) for Vigna radiata and Cicer arientinum. The reduction of germination can be also due to the presence of high levels of detected heavy metals in water from the canal. As reported by Talukdar (2011), Aresnic (30 and 40 mg/L) can effect germination of Trigonella foenum-graecum L. and Lathyrus sativus L. Also, Cr in amounts exceeding 500ppm decreased germination of beans by 48% (Parr and Taylor 1982), of beet root by 32-57% (20-80ppm) (Jain, 2000), and of alfalfa seed by 23% at rates 40ppm (Peralta et al., 2001).
Root elongation of maize and barley (F=3.64**, 5.43**, P<0.01), was highly significantly inhibited by water from Aleksandrovački canal. On the other hand, some specific synergistic effect of all compounds from the water sample on seedlings root growth of white mustard was recognized since it was significantly stimulated by water (F=11.92**, P<0.01). Cucumber seedlings root (F=0.26 ns, P>0.05) was not under the influence of water quality. A number of authors reported different effects of irrigation water on root length. Schier (1985) and Wong and Chu (1985) pointed out that different plants show significant reduction in growth parameters when irrigated with polluted water. Also, according to Gvozdenac et al. (2012) root elongation of maize, cucumber and barley were inhibited by interstitial water contaminated with Cr. Also, Mehta and Bhardwaj (2012) found that water rich in BOD and COD as well as total dissolved solids significantly reduced seedlings growth of Vigna radiata and Cicer arientinum. Potential effect of heavy metal pollution of water from Aleksandrovački canal on tested species should be also recognized. This is in accordance with Liu et al. (2007) who detected a reduction in root length as a result of As-induced toxicity (5-20 mg/kg) and of Barcelo et al. (1986); Barton et al. (2000); Chen et al. (2001) indicating that Cr, also detected in high content in this work, is potential cause for root inhibition of cultivated plants. The opposite results indicating a positive effect of mixed water pollution are presented by several authors. Gafoor et al. (1994) reported that irrigation water containing plant nutrients and organic matter, high concentration of soluble salts and heavy metals can stimulate growth of a number of plant species. Also, waste water containing nutrients of fertilizing value, especially nitrogen, can enhances plant growth and yield of crop plants (Soumare et al. (2003); Gupta et al. (2005); Afroza (2008)), which was also proved in our work for white mustard.
Shoot length of barley, cucumber and white mustard seedlings (F=0.58 ns, 0.27 ns, 2.44 ns, P>0.05, respectively) were not under the influence of water quality and/or mixed pollution, which was also reported by a number of researchers (Schulz and Liess 1999, Scheurell et al. 2007, Gvozdenac et al. 2011, 2012) while maize shoot was stimulated by water from Aleksandrovački canal (F=2.95**, P<0.01). According to Marshner (2002) water rich in essential elements like nitrogen can enhance seedlings growth when used for irrigation.